by Christine Mlot

For most of the year, the Karner blue butterfly exists as a tiny, dimpled white egg. But as winter days lengthen into spring, the life inside begins to stir, and soon a pale green caterpillar emerges. It feeds, then cloaks itself in a chrysalis. And then, for one brief week, the Karner blue is on the wing.

Or, a wing and a prayer.

For decades, the butterfly with the fleeting appearance was on the verge of becoming a fleeting species as its oak savannas and pine barrens disappeared. Now, with efforts to restore its preferred habitat and raise the butterflies in captivity, the Karner blue's future is decidedly more upbeat.

The rare blue butterfly lives for the wild blue lupine. When Karner eggs hatch in April, lint-sized caterpillars emerge to feed on the leaves of the newly sprouted plant. Nothing else will do. And when the mature butterflies are looking to lay eggs for a second brood, again, they've only got eyes for lupine.

Where the plant takes root, the butterflies usually follow. Lupine thrives in sandy soil amid the sunny openings of pine barrens and oak savannas. Once, fires created prime conditions for the lupine, sustaining butterfly populations along a band hugging the Great Lakes from Minnesota to Maine. But as fires were suppressed, brush took over the sunny spaces, and the savannas' scattering of trees turned into dense forest lots. Or parking lots.

As the Karner's quest for lupine became increasingly quixotic, its own numbers declined. In 1992 the federal government placed the butterfly on the endangered species list.

Fifteen years later, the outlook for the Karner is no longer so blue. From the pine barrens of upstate New York to the black oak savannas of northern Indiana, hundreds of acres of lupine habitat have been restored and reconnected, allowing the Karner to reclaim lost territory and allowing conservationists to reintroduce it to its traditional fluttering grounds.

To see the Karner blue in spring is to see one of nature's most colorful—and color-coordinated—spectacles. In May, as the blooms of the lupine begin to unfold, so too do the Karners, turning the savannas into a rhapsody in every shade of violet and blue.

But you've got to be quick, and a little bit lucky, to behold it. If the sun doesn't cooperate and warm things up, the Karner blues won't fly at all. Even if they do fly, the tiny butterflies —about the size of a thumbnail—stay close to the ground, flitting among the wildflowers, sipping nectar and moving pollen. Within a week or so, the improvised harmony comes to an end: The lupine goes to seed; the butterflies start to look raggedy.

And then they're gone.

In July another brood of Karner blues comes to life. While their blue-winged flight is often more abundant, it's absent the blooming accompaniment. The mood,  less blue.

The little blue butterfly has long been a cause célèbre, and its comeback has become a cause for celebration. Karner blue festivals have popped up from New York to Wisconsin, and the Karner is the official butterfly of the state of New Hampshire and the town of Queensbury, New York. The Department of Natural Resources in Wisconsin even runs a seasonal hot line for reports of Karners in flight.

As the savannas are restored, the return of the Karners provides the finishing touch. Says Paul Labus of The Nature Conservancy in Indiana, "Seeing them flying again makes everything look just right."